Various types of software use a central processing unit (CPU) in combination with a graphics processing unit (GPU) to display graphics on a display. Examples of such software are window managers, three-dimensional games, animation software, application software, and others. Typically, events such as user inputs or interactions with a user interface, animations, video playbacks, system events that require the display of information, or other events require both application-level logical processing to determine, for example, what objects may need to be displayed or moved, what object portions have been hidden or exposed, textures to be rendered, user interface elements to draw, and other logical operations that, perhaps by way of an application programming interface, generate code or instructions to be executed on a GPU.
Various approaches have been used to improve the flow of work between the CPU and the GPU and overall computational efficiency. For example, double buffering has been used to improve speed and triple buffering has been used to allow for some CPU-GPU concurrency. A technique referred to as vsync (vertical synchronization), which synchronizes graphics generation and painting with display refreshes, has been used to avoid artifacts such as tearing. There remains a need to improve overall throughput when the vsync approach is used. Some previous approaches have improved overall throughput but at the expense of artifacts such as skipped frames or at the cost of increased hardware requirements, which can be problematic for resource-constrained devices. It would be beneficial if overall throughput could be improved with the vsync technique without introducing unacceptable lag (delay from event to corresponding display of graphics), stuttering, or other undesirable side effects.
Techniques related to CPU-GPU parallelization are discussed below.